Gravity Probe B, to be launched next Monday, is an experiment to test Einstein’s general theory of relativity, which predicted the expansion of the universe and the existence of black holes.

The probe contains four gyroscopes and squids (superconducting quantum interference devices) to measure whether and how the spinning Earth twists space-time (frame dragging) and makes space-time sag (gamma).

It will give physicists precise measurements on ways that matter warps space-time to produce gravity, allow them to calibrate the black hole dynamos that produce the energies of quasars, and perhaps find evidence of new forces in the universe.